The present invention relates to a linkage mechanism which is suitable for operative association between a fifth wheel of a drive vehicle and a steerable rear axle of, for example, a trailer unit.
The term "steerable rear axle" is intended to embrace a pivotable rear axle/rear wheel assembly, as well as, pivotable rear wheels connected to a rear axle steerable under the influence of a king pin steering system.
U.S. Pat. No. 5,201,836 discloses a steering mechanism comprising a pivotal lever and a pin extending from a fifth wheel. The pin extends through an arcuate slot and then through an elongated slot in the lever. In use, the pin moves along the arcuate slot whilst moving longitudinally in the elongated slot. U.S. Pat. No. 5,201,836 does not disclose or even suggest a cam collar comprising a substantially round section opening into a substantially elliptic section.